Estimation of the rootzone depth above a gravel layer (in wild blueberry fields) using electromagnetic induction method     

Fahad S. Khan  Qamar U. Zaman  Young K. Chang  Aitazaz A. Farooque  Arnold W. Schumann  Ali Madani 《Precision Agriculture》2016,17(2):155-167

Wild blueberry (Vaccinium angustifolium Ait.) fields in the north east Canada are naturally grown in a course textured thin layer of soil and below this layer is a soilless layer of gravel. The root zone depth of this crop varies from 10 to 15 cm. Investigating the depth to the gravel layer below the course textured soil is advantageous, as it affects the water holding capacity of the root zone. Water and nutrient management are the two primary determinants of crop yield and the amount of leaching. The objective of this study was to estimate the depth to the gravel layer using DualEM-2 instrument. A C++ program written in Visual Studio 2010 was used to develop mathematical models for estimating the depth to the gravel layer from the outputs of DualEM-2 sensor. Two wild blueberry fields were selected in central Nova Scotia, Canada to evaluate the performance of DualEM-2 instrument in estimating the rootzone depth above the gravel layer. The mid points of squares created by grid lines were used as the sampling points at each experimental site. The actual depth to the interface was measured manually at selected grid points (n = 50). The apparent ground conductivity (EC_a) values of DualEM-2 were recorded and the depth to the interface was estimated for the same sampling points within the selected fields. The fruit yield samples were also collected from the same grid points to identify the impact of the depth to the gravel layer on crop yield. After calibrations, comprehensive surveys were conducted and the actual and estimated depths to the interface were established. The interpolated maps of fruit yield, and the actual (z_in) and estimated (\( {\text{z}}_{\text{in}}^{*} \)) depths to the interface were created in ArcGIS 10 software. Results indicated that the z_in was significantly correlated with \( {\text{z}}_{\text{in}}^{*} \) for the North River (R ² = 0.73; RMSE = 0.27 m) and the Carmel (R ² = 0.45; RMSE = 0.20 m) sites. Results revealed that the areas with shallow depth to the gravel layer were low yielding, indicating that the variation in the depth to the gravel layer can have an impact on crop productivity. Non-destructive estimations of the depth to the gravel layer can be used to develop erosion control strategies, which will result in an increased crop production.  相似文献   

Effect of tebuconazole-tolerant and plant growth promoting Rhizobium isolate MRP1 on pea–Rhizobium symbiosis     

Munees Ahemad  Mohammad Saghir Khan 《Scientia Horticulturae》2011

Seed dressing with fungicides adversely affects the structure and function of beneficial soil microbial communities and consequently crop yield. This study was aimed to evaluate the impact of technical-grade fungicide tebuconazole on plant growth promoting potentials of tebuconazole-tolerant Rhizobium isolate MRP1. The performance of the isolate MRP1-inoculated pea plants grown in tebuconazole treated soils was also assessed. Generally, the three concentrations [100 (recommended dose), 200 and 300 μg kg⁻¹ soil] of tebuconazole when used alone, adversely affected the growth, symbiosis, grain yield and nutrient uptake by pea plants. Concentration dependent phytotoxicity of tebuconazole was observed for all the measured parameters. On the contrary, fungicide tolerant Rhizobium sp. MRP1 in the presence of fungicide increased the measured parameters at all tested concentrations. As an example, when inoculant MRP1 was also used with 300 μg tebuconazole kg⁻¹ soil, it substantially increased the root nitrogen, shoot nitrogen, root P, shoot P, seed yield and grain protein by 20, 19, 50, 31, 15 and 7%, respectively, when compared with uninoculated plants grown in fungicide-treated soils. The study suggests that the plant growth promoting Rhizobium sp. MRP1 can be used as bacterial inoculant to increase the production of pea in soils polluted with fungicides.  相似文献   

Biological activity of peanut (Arachis hypogaea) phytoalexins and selected natural and synthetic Stilbenoids     

Sobolev VS  Khan SI  Tabanca N  Wedge DE  Manly SP  Cutler SJ  Coy MR  Becnel JJ  Neff SA  Gloer JB 《Journal of agricultural and food chemistry》2011,59(5):1673-1682

The peanut plant (Arachis hypogaea L.), when infected by a microbial pathogen, is capable of producing stilbene-derived compounds that are considered antifungal phytoalexins. In addition, the potential health benefits of other stilbenoids from peanuts, including resveratrol and pterostilbene, have been acknowledged by several investigators. Despite considerable progress in peanut research, relatively little is known about the biological activity of the stilbenoid phytoalexins. This study investigated the activities of some of these compounds in a broad spectrum of biological assays. Since peanut stilbenoids appear to play roles in plant defense mechanisms, they were evaluated for their effects on economically important plant pathogenic fungi of the genera Colletotrichum, Botrytis, Fusarium, and Phomopsis. We further investigated these peanut phytoalexins, together with some related natural and synthetic stilbenoids (a total of 24 compounds) in a panel of bioassays to determine their anti-inflammatory, cytotoxic, and antioxidant activities in mammalian cells. Several of these compounds were also evaluated as mammalian opioid receptor competitive antagonists. Assays for adult mosquito and larvae toxicity were also performed. The results of these studies reveal that peanut stilbenoids, as well as related natural and synthetic stilbene derivatives, display a diverse range of biological activities.  相似文献   

Pseudomonasaeruginosa strain PS1 enhances growth parameters of greengram [Vignaradiata (L.) Wilczek] in insecticide-stressed soils     

Munees Ahemad  Mohammad Saghir Khan 《Journal of pest science》2011,84(1):123-131

Plant growth promoting rhizobacteria (PGPR) are known to increase growth and vigor of legumes in conventional cropping systems. Considering this as a basis, this study was aimed at identifying phosphate-solubilizing (PS) rhizobacterial strains expressing higher tolerance to insecticides, fipronil and pyriproxyfen, and synthesizing plant growth regulators even amid insecticide stress. The impact of selected rhizobacteria endowed with multitude of activities was investigated on greengram, grown in soils treated with different concentrations of insecticides. The fipronil and pyriproxyfen tolerant Pseudomonas aeruginosa strain PS1 produced plant growth promoting substances, both in the presence and absence of the insecticides. Both insecticides at recommended and higher rates, in general, had phytotoxic effects and decreased phytomass, symbiotic properties, nutrients uptake, and seed yield of greengram plants. Interestingly, P. aeruginosa PS1 even when used with all concentrations of the two insecticides significantly increased the measured parameters at 50 and 80 days after sowing, compared to the plants grown in soils treated with the same concentration of each insecticide but without inoculants. P. aeruginosa PS1 can be used as biofertilizer to augment the growth of greengram exposed to insecticide-stressed soils.  相似文献   

Insecticide-tolerant and plant-growth-promoting Rhizobium improves the growth of lentil (Lens esculentus) in insecticide-stressed soils     

Ahemad M  Khan MS 《Pest management science》2011,67(4):423-429

BACKGROUND: Application of insecticides in modern agriculture in order to enhance legume production has led to their accumulation in soils to levels that adversely affect soil microflora such as rhizobia and exert a negative impact on the physiological activities associated with them. This study was therefore designed to identify rhizobial strains expressing higher tolerance to insecticides fipronil and pyriproxyfen and synthesising plant growth regulators even amid insecticide stress. RESULTS: The fipronil‐ and pyriproxyfen‐tolerant Rhizobium sp. strain MRL3 produced plant‐growth‐promoting substances in substantial amounts, both in the presence and in the absence of the insecticides. In general, both insecticides at recommended and higher rates reduced plant dry biomass, symbiotic properties, nutrient uptake and seed yield of lentil plants. Interestingly, when applied with any concentration of the two insecticides, Rhizobium sp. strain MRL3 significantly increased the measured parameters compared with plants grown in soils treated solely with the same concentration of each insecticide but without inoculant. CONCLUSION: This study suggests that Rhizobium strain MRL3 may be exploited as a bioinoculant to augment the efficiency of lentil exposed to insecticide‐stressed soils. Copyright © 2010 Society of Chemical Industry  相似文献   

Metabolism tissue distribution, and elimination of cis-[14C]chlordane in the tropical freshwater fish Cichlasoma sp     

M Feroz  M A Khan 《Journal of agricultural and food chemistry》1979,27(6):1190-1197

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Combinatorial approach to flavor analysis. 2. Olfactory investigation of a library of S-methyl thioesters and sensory evaluation of selected components.     

C Berger  N Martin  S Collin  L Gijs  J A Khan  G Piraprez  H E Spinnler  E N Vulfson 《Journal of agricultural and food chemistry》1999,47(8):3274-3279

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Structure and stability of soil aggregates     

K. Yu. Khan  A. I. Pozdnyakov  B. K. Son 《Eurasian Soil Science》2007,40(4):409-414

The formation and disintegration of macroaggregates into water-stable particles in a wide range of soil water contents—from the hygroscopic moisture to the capillary saturation moisture—were analyzed. It was found that the disintegration of macroaggregates into water-stable particles follows an exponential law. As the system becomes a three-phase system, neighboring particles in the macroaggregate are pressed together due to capillary pressure, and strong molecular bonds are formed. The disintegration curve of macroaggregates is an integral informative characteristic, which reflects the dynamics of changes in the strength properties of the macroaggregates.  相似文献   

New alkamides from maca (Lepidium meyenii)     

Zhao J  Muhammad I  Dunbar DC  Mustafa J  Khan IA 《Journal of agricultural and food chemistry》2005,53(3):690-693

Maca (Lepidium meyenii) has been used as a food in Peru for thousands of years. More recently a wide array of commercial maca products have gained popularity as dietary supplements, with claims of anabolic and aphrodisiac effects, although the biologically active principles are not fully known. In an earlier chemical investigation, two new alkamides and a novel fatty acid, as well as the N-hydroxypyridine derivative, macaridine, were isolated from L. meyenii. Further examination has led to the isolation of five additional new alkamides, namely, N-benzyl-9-oxo-12Z-octadecenamide (1), N-benzyl-9-oxo-12Z,15Z-octadecadienamide (2), N-benzyl-13-oxo-9E,11E-octadecadienamide (3), N-benzyl-15Z-tetracosenamide (4), and N-(m-methoxybenzyl)hexadecanamide (5). Their structures were established by spectrometric and spectroscopic methods including ESI-HRMS, EI-MS, (1)H, (13)C, and 2D NMR, as well as (1)H-(15)N 2D HMBC experiments. In addition, the identity of N-benzyl-15Z-tetracosenamide (4) was confirmed by synthesis. These compounds have been found from only L. meyenii and could be used as markers for authentication and standardization.  相似文献   

Yield Responses of Wheat to Ozone Exposure as Modified by Drought-Induced Differences in Ozone Uptake     

Khan  S.  Soja  G. 《Water, air, and soil pollution》2003,147(1-4):299-315

Over a period of two years greenhouse experiments were carried out to quantify the interaction ozone exposure × water stress in winter wheat (Triticum aestivum L. cv. Perlo). Assessment of effects carried out on various yield parameters showed that abundant water supply made the plants most sensitive to ozone exposure. In well-watered plants (75%) of soil water capacity, s.w.c.), the AOT40 ozone exposure doses of 26.8 and 24.9 μmol mol^-1 hr^-1 (ppm.h) caused grain yield reductions by 35 and 39%. No reductions of yields were observed at severe water stress (35% of s.w.c.) condition. The decrease in ozone responsiveness under drought can be explained by a distinct reduction in ozone uptake (18 vs. 2 mmol m^-2 in well-watered vs. severely stressed plants at the same ozone exposure). The calculations of ozone uptake were based onrepeated measurements of leaf conductance. Generally curvi-linear regression functions explained the dependence of relative yield on ozone and on water stress better than multiple simple linear regression functions. The consideration of ozone uptake instead of ozone exposure improved the performances of the models further. For explaining grain yield, 96.8% of the variances could be explained by a model resulting from curvi-linear regression fitting. A suggestion for calculating correction factors to modify critical levels in the case of limited water supply is presented.  相似文献